[tangent]
railway lights have long hoods to shield the bulb from sunlight and these are prone to snow build up that can block out the light above... therefore the bottom light is always free from obstruction whilst the others might not be... and red goes at the bottom so its always visable!
[/tangent]

[tangent]
railway lights have long hoods to shield the bulb from sunlight and these are prone to snow build up that can block out the light above... therefore the bottom light is always free from obstruction whilst the others might not be... and red goes at the bottom so its always visable!
[/tangent]